The global TFR has been tracking downward over the past few decades.Therefore we can assume that it will continue to track downward and global population will stabilise, then decline and everything will be alright eh? This is the common line of reasoning by most demographers, economists and politicians. However the past is not always the best predictor of the future. I will use New Zealand’s TFR to demonstrate my point (Fig. 1).
Figure 1. New Zealand TFR 1921 – 2011
A demographer living in the early 1930s would be almost certain that New Zealand’s TFR was heading for replacement level and below within a few years. However, with the onset of World War 2 the TFR began to skyrocket and continued to climb for some years after the war ended. I will not expand on the sociological reasons for such a dramatic change in TFR, however, we can safely say that this increase in TFR more than made up for the men and women lost in the war and has led to New Zealand having a much larger population than it would have had TFR reached replacement level or below in the late 1930s or early 1940s.
Therefore just because New Zealand’s TFR is currently around replacement level we cannot accurately predict that it will continue to decrease or increase or oscillate around current levels. The implication is that we should not assume that New Zealand and the World’s population will stabilise, then decline and everything will be alright. We must continue to take action to ensure that people understand the consequences of continued population growth and empower them to make the right decisions for the sake of future generations.